In this study, a series of six experiments examined the online and offline relative clause attachment preferences of English monolingual speakers, Korean monolingual speakers, and late Korean/English bilingual speakers when processing globally ambiguous English and Korean relative clauses. Results showed that both the English monolingual group and the Korean/English bilingual group showed effects of working memory capacity (WMC) in the interpretive and post-interpretive stages of processing, providing support for the Single Resource model (Just & Carpenter, 1992). The monolingual English and monolingual Korean low-span groups showed evidence of being more susceptible to changes in processing difficulty, while neither the low-spans nor high-spans in the bilingual group showed evidence of being affected by these changes. Furthermore, the monolingual participants were more affected by syntactic factors, whereas the bilingual participants were more affected by lexical factors. These results suggest that the processing of bilingual readers may be qualitatively different from the processing of monolinguals (Clahsen & Felser, 2006). Further analysis showed that these differences were not due to a lack of cognitive resources, i.e., WMC. Finally, results from the six experiments showed that although cross-linguistic differences in relative clause attachment may exist, the disambiguation strategies chosen by all three populations may be affected to a greater extent by factors such as sentence complexity and WMC.